My main shooting buddies will absolutely not shut up about how "impractical" of a deer rifle my 20 inch AR-10 (308) with 5-30x scope is.
If I had a desire to kill a deer with it, that deer would DIE. But, uh, not exactly the point.
(Edit to elaborate/clarify: I don't have any particular desire to hunt, so I am annoyed that my friends insist on discussing the suitability of my long distance precision target rifle for hunting. That said, if I indeed did desire to hunt with it, it would be more than adequate for the task)
Removed by mod
AR 15 is 223, though there's kits to convert it to virtually any round.
AR 10 is 308.